1. Field of the Invention
The present invention relates generally to snowmaking equipment. More particularly, this invention relates to single, four-step and six-step snowmaking guns particularly useful for producing snow at ski resorts and anywhere else that has sufficiently cold atmospheric conditions.
2. Description of Related Art
The production of artificial snow is well known in the art. Conventional snow guns or snow lances of various forms find application particularly in winter sports areas. According to one known method, a jet of ice nuclei, or seed crystals, is produced in a “nucleator nozzle” and is brought into contact with a jet composed of water droplets some distance above ground in the atmosphere. By means of said “germination”, or “seeding”, snow is produced from the cooling water droplets prior to falling on the ground.
In order to produce the ice nuclei, water is cooled and atomized, typically with the use of compressed air. An essential parameter for economical operation of nucleator nozzles of this type is the quantity of compressed air which has to be used to achieve significant and useful snow production. The quantity of compressed air generally determines the energy input and ultimately the operating costs of such snowmaking systems. A further essential operating parameter relates to the wet bulb temperature of the atmospheric surroundings. Conventional snow lances, are known to produce artificial snow up to approximate −3° C. It would be desirable to produce artificial snow at even higher temperatures with less energy input.
Convergent nucleator nozzles are known to produce ice nuclei. In a convergent nozzle, the cross-section in the nozzle fluid channel becomes continuously narrower in the direction of the exit orifice. Examples of such convergent nucleator nozzles include, e.g., FR 2 617 273, U.S. Pat. No. 4,145,000, U.S. Pat. No. 4,516,722, U.S. Pat. No. 3,908,903 or FR 2 594 528. In addition, convergent-divergent nucleator nozzles in accordance with the Laval principal are also known. Nucleator nozzles of this type are shown, e.g., in U.S. Pat. No. 4,903,895, U.S. Pat. No. 3,716,190, U.S. Pat. No. 4,793,554 and U.S. Pat. No. 4,383,646. However, these conventional nucleator nozzles generally require a relatively large energy input in order to produce the nuclei.
Snow lances in which nucleator nozzles and water nozzles are arranged adjacent to one another on a lance body such that the ice nuclei and water droplets produced are brought into contact with one another in a germination zone adjacent to the lance body are well known. Solutions of this type are shown, for example, in DE 10 2004 053 984 B3, U.S. Patent Pub. No. 2011/0049258, U.S. Pat. No. 7,114,662, U.S. Pat. No. 6,508,412, U.S. Pat. No. 6,182,905, U.S. Pat. No. 6,032,872 and U.S. Pat. No. 5,810,251. However, most conventional nucleator nozzles and snow lances can only be used at relatively low atmospheric and water source temperatures. Additionally, such conventional snow guns generally have little range of snowmaking output.
There is a need for improved snowmaking guns that produce snow at higher temperatures, using less energy and producing more snow than conventional snow guns. It would be particularly useful to have a snowmaking gun that has discrete levels or steps of snowmaking production capability to adjust production on the fly.